After giving Mom a necklace with a key-shaped pendant on it, Harry and his Dino pals are dying to know what the key opens and they head to Dino World on their new quest to find the matching lock. Princess Pamela’s castle seems to be the perfect place to start, but the royal pets Max and Muffin have other ideas and decide to take the opportunity to make a getaway – taking the key with them! Princess Pam’s naughty pets lead Harry and the gang on a wild goose chase around Dino World. But as luck would have it, Max and Muffin aren’t so bad after all as they lead Harry and the Dinos to the ideal spot to try out their key: a valley full of doors! It’s just a case of finding the right one and seeing where it leads...